JP2000232539A - Power feeder circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the workability having been required for polarity check at a plurality of connections in order to prevent misconnection in a subscriber line used for call receiving/transmission control. SOLUTION: The power feeder circuit has a circuit 204 that monitors repetition of detection/non-detection of a loop current by utilizing characteristics of repeating the detection/non-detection of the loop current that is caused when a 2-wire metallic cable is misconnected, and a circuit 205 that discriminates the misconnection of the cable on the occurrence of the repetition to automatically invert the polarity so as to solve disabled communication.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit,
The present invention relates to a power supply circuit with an automatic polarity correction device suitable for SDN subscriber line termination.

[0002]

2. Description of the Related Art In a subscriber data communication system,
DSU (Digital Serv) at the station equipment and the subscriber's home
ice Unit), once the M
DF (Main Distribution Facility)
(the main wiring board) to connect to the two-line metallic subscriber line. Furthermore, it connects to the protector in the immediate vicinity of the subscriber's house, and is then pulled into the modular at the user's house.

[0003] ISDN (Integrated Ser.)
In the case of a services digital network (Integrated Services Digital Network) line, a + potential is applied to one line L1 and a-potential is applied to the other line L2 of the two-line metallic subscriber line (this is called normal polarity), and outgoing and incoming call control is performed. In performing this, the potential of L1 is inverted to a negative potential, and the potential of L2 is inverted to a positive potential (this is called a reverse polarity).

FIG. 3 is a block diagram showing such a conventional power supply circuit configuration. Power is supplied to the two-wire metallic cable from the remote power supply power supply 301 via the normal power supply relay 306 and the reverse power supply relay 307. This power supply 30
1 is connected to a loop current detection circuit 303 and a data transmission / reception / normal / reverse control circuit 302. A normal power supply relay control signal and a reverse power supply relay control signal are applied to the relays 306 and 307 from the N and R terminals of the control circuit 302, respectively. By these relay control signals, the relays 306 and 307 operate, respectively, and when the relay 306 is turned on, the power supply voltage of the power supply 301 has the normal polarity described above, and when the relay 307 is turned on, the power supply voltage of the power supply 301 has the reverse polarity. This will be applied to the two-wire metallic cable.

[0005]

However, the conventional power supply circuit described above has several problems or disadvantages as follows.

[0006] First, a method is adopted in which outgoing / incoming call control is realized by utilizing the change in the polarity of the voltage applied to the two-wire metallic cable.
In all of the plurality of connection points, it is necessary to check the polarity using a tester or the like.

[0007] In addition, there are many cases in which two-wire metallic cable is laid before starting the service, and it is possible to perform a check in a state where power is not supplied from the station apparatus. There is a possibility that a connection error may occur due to a mistake. Therefore, there is a case where there are a plurality of connection points, and an erroneous connection is caused at each connection point, and line connection becomes impossible. Normally, when switching from an analog telephone, it is only necessary to connect the modular cable of the telephone to the DSU. is there.

Accordingly, an object of the present invention is to provide a power supply circuit capable of preventing erroneous connection by automatically correcting the polarity of a two-wire metallic cable.

[0009]

In order to solve the above-mentioned problems, a power supply circuit according to the present invention employs the following characteristic configuration.

(1) A power supply circuit for supplying power to a two-wire metallic cable, a loop current detection circuit, a data transmission / reception / normal reverse control circuit, and a normal / reverse power supply relay. A power supply circuit provided with a polarity inversion circuit for inverting the polarity of the power supply for power supply in accordance with detection / non-detection of a loop current.

(2) The power supply circuit according to the above (1), wherein the polarity inversion circuit counts the number of repetitions of the detection / non-detection of the loop current, and performs the inversion control when the number reaches a predetermined number.

(3) The above (1) or (2), wherein an incorrect connection detection / polarity inversion control circuit is provided to control the polarity inversion circuit.
Power supply circuit.

(4) The power supply circuit according to (1), (2) or (3), wherein the polarity inversion circuit is formed by a relay.

(5) The power supply circuit according to (1), (2), (3) or (4), wherein the polarity inversion circuit is disposed between the normal / reverse power supply relay and the power supply power supply.

(6) The power supply circuit according to any one of (1) to (5), which is used for a line termination device in a station.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a power supply circuit according to the present invention will be described below in detail with reference to FIGS.

FIG. 1 is a connection diagram of a two-wire metallic cable using a power supply circuit according to the present invention, showing an example of a connection state from a station apparatus to a DSU at a subscriber's house. Office building 10
Includes a switch 100, a line terminating device 101, an MDF 10
2. An in-station protector 103 is provided. On the other hand, the subscriber home 20 has a modular jack 106, a DSU 107
And a telephone (TE) 108. Further, between the station building 10 and the subscriber home 20, there is a subscriber line having an imaginary connection unit 104 and a protector 105.

A power supply circuit according to the present invention, which will be described later, is mounted on a line termination device 101 of an intra-office device. Two-line metallic cables L1 and L2 are drawn out from the OCU package of the line terminating device 101 for each subscriber line, and are connected to a terminal board MDF102 as a first connection point. MDF
From 102, it is connected to the intra-office protector 103 which is the second connection point. The intra-station protector 103 is connected to the modular jack 1 of the subscriber's home 20 via a plurality of overhead connection parts (central part) 104 and further via a protector 105 near the subscriber's home 20.
06.

Next, a block diagram of a preferred embodiment of a power supply circuit according to the present invention will be described with reference to FIG. Since this power supply circuit is similar to the conventional circuit of FIG. 3, the description will focus on the differences. This power supply circuit includes a remote power supply power supply 20.
1. Data transmission / normal / reverse control circuit 20
2, a loop current detection circuit 203, an erroneous connection detection / polarity inversion control circuit 204, a polarity inversion circuit 205, a normal power supply relay 206, and a reverse power supply relay 207.

Normal / reverse relays 206 and 20
7 is normally connected, the DC voltage supplied from the remote power supply power supply 201 passes through the polarity inversion circuit 205 with a positive polarity (position shown), Normal power is supplied to the subscriber via the normal power relay 206. In this case, since the loop current detection circuit 203 does not detect the loop current, the data transmission / reception / normal / reverse control circuit 202 maintains the normal power supply relay control and continues normal power supply. In addition, the polarity inversion circuit 205 maintains the positive polarity because the misconnection detection circuit 204 does not detect the misconnection.

Next, when an incoming call is received from the exchange 100, the data transmission / reception / normal / reverse control circuit 202
Operates the reverse power supply relay 207 to perform reverse power supply to the subscriber. In the loop current detection circuit 204,
It detects that the loop current is flowing normally and shifts to the communication state.

The case where the two-wire metallic cable is incorrectly connected will be described. In this case, the DC voltage supplied from the power supply 201 passes through the polarity inversion circuit 205 with a positive polarity, passes through the normal power supply relay 206, and attempts to perform normal power supply to the subscriber. However, reverse power is supplied due to incorrect connection. At this time, the loop current detection circuit 203
Then, the data transmitting / receiving unit 202 operates the reverse power supply relay 207 to perform reverse power supply, but returns to normal power supply due to erroneous connection. Since the loop current detection circuit 203 does not detect the loop current, the data transmission / reception circuit 202
To return to the previous state, and repeat this series of operations.

The incorrect connection detection / polarity inversion control circuit 204
It monitors the detection / non-detection of the loop current and counts a certain number (preset) of loop current detection / non-detection.
It is determined that the wire metallic cable is incorrectly connected.
Therefore, the polarity inversion circuit 205 is operated to invert the relay contact to the position shown in FIG. 2 to forcibly correct the erroneous connection. As a result, the erroneous connection is automatically corrected.

The preferred embodiment of the power supply circuit according to the present invention has been described above in detail. However, the present invention should not be limited to only such preferred embodiments, and those skilled in the art can easily understand that various modifications can be made as necessary. For example, the polarity inversion circuit 205 does not necessarily need to be connected to the position shown in FIG. 2, and can be provided at an arbitrary position between the power supply 201 and the subscriber line.

[0025]

As will be understood from the above description, the power supply circuit of the present invention has various practical effects. First, since there is a circuit for monitoring erroneous connection of a subscriber line and automatically correcting the erroneous connection, communication failure due to erroneous connection of a two-wire metallic cable can be prevented. In addition, since an automatic polarity correction circuit is provided, the construction worker does not need to check the polarity at a plurality of connection points, and only has to perform the connection work. Therefore, the workability of connecting a two-wire metallic cable is greatly improved. Is possible.

[Brief description of the drawings]

FIG. 1 is a connection example of a two-wire metallic cable using a power supply circuit according to the present invention.

FIG. 2 is a block diagram of a preferred embodiment of a power supply circuit according to the present invention.

FIG. 3 is a block diagram of a power supply circuit of a conventional subscriber communication device.

[Explanation of symbols]

Reference Signs List 201 power supply power supply 202 data transmission / reception / normal / reverse control circuit 203 loop current detection circuit 204 incorrect connection detection / polarity inversion control circuit 205 polarity inversion circuit 206, 207 normal / reverse power supply relay

Claims (6)

[Claims] 1. A power supply circuit having a power supply for supplying power to a two-wire metallic cable, a loop current detection circuit, a data transmission / reception / normal reverse control circuit, and a normal / reverse power supply relay. A power supply circuit, comprising: a polarity inversion circuit that inverts the polarity of the power supply for power supply in accordance with detection / non-detection of a current. 2. The power supply circuit according to claim 1, wherein the polarity inversion circuit counts the number of times of detection / non-detection of the loop current and performs inversion control when the number of times reaches a predetermined number. 3. The power supply circuit according to claim 1, further comprising an erroneous connection detection / polarity inversion control circuit for controlling the polarity inversion circuit. 4. The power supply circuit according to claim 1, wherein the polarity inversion circuit is formed by a relay. 5. The power supply circuit according to claim 1, wherein the polarity inversion circuit is arranged between the normal / reverse power supply relay and the power supply power supply. 6. The power supply circuit according to claim 1, wherein the power supply circuit is used for a line termination device in a station.